1. Field of the Invention
This invention relates to an optical package and an optical transceiver with a locking mechanism operable to be detachably placed in a host instrument and, more particularly to, an optical package and an optical transceiver with a locking mechanism that can be easily detached from the host instrument.
2. Description of the Related Art
In a host instrument, an optical transceiver which is actually served for optical communication (which means only mutual conversion of optical signals and electrical signals in a narrow sense, while it involves also protocol processing in a lower hierarchy in a broad sense) through connection of optical fiber is incorporated.
There are two types of optical transceiver, and one of them is a stationary type transceiver which is incorporated into a host instrument, and connected and secured to an inside base plate of a host instrument by means of solder and the like; and the other is a pluggable type transceiver which is applied in such that the transceiver is inserted into a window which has been previously provided on the host instrument. Such optical transceiver of a pluggable type can be replaced in response to some troubles or a variety of communication specifications.
The inside of a host instrument is provided with a container having an opening on either side thereof called by the name of “cage” for containing an optical transceiver of a pluggable type therein which is inserted through a window, and further connection terminals for electrical connection (receiving side) are disposed on the innermost part of the cage. The optical transceiver is arranged in such that optical devices and electronic circuits required for light transmission and reception are contained in a substantially rectangular parallelepiped transceiver main body, and an end of the transceiver main body is provided with connection terminals for electrical connection (side to be inserted). Thus, when the optical transceiver is inserted into the cage through the window, both the connection terminals are electrically connected with each other, whereby it becomes possible to transmit information between the host instrument and the optical transceiver.
A pluggable type optical transceiver is provided with a locking mechanism for preventing such a possibility that the optical transceiver detachable to the host instrument is fallen away from the host instrument due to unforeseen oscillations or impact shocks, or maintaining a positive condition of electrical connection between the optical transceiver and the host instrument. More specifically, the transceiver main body is provided with a member engaging with the cage being a part of the host instrument, the member moving to a direction perpendicular to a direction along which the optical transceiver is inserted into the cage in the case when the optical transceiver is in a position where a positive electrical connection is kept in the connection terminals. The member moves in the direction perpendicular to that along which the optical transceiver is inserted into the cage to engage therewith, and hence, the optical transceiver is locked. On the other hand, when the member moves up to a position where the member is disengaged with the cage, the optical transceiver may be extracted.
For an operation of shifting the member from a position where the member to be engaged with the cage to a position where the member to be disengaged with the cage, heretofore a latch member is disposed inside the optical transceiver. Since the latch member is positioned in the innermost place of the optical transceiver so as to engage with the cage, such a movable member is required for operating the latch member from the outside of the window in the host instrument. Namely, a part of the movable member reaches the latch member, while another part of which can be observed from the outside of the window in the host instrument.
In FIGS. 1A and 1B, an essential part of a locking mechanism disclosed in U.S. Pat. No. 6,439,918 is shown. The locking mechanism shown in FIG. 1A involves a latch member 74 which functions to restrict extraction of a transceiver main body (a movement towards the left side in the drawing) as a result of fitting the latch member into a port 73 formed on the undersurface of a cage 72 so as to protrude from the undersurface 71 (represented by the alternate long and short dash line) of the transceiver main body. The latch member 74 contains a vertical plane 75 which outgoes vertically from the undersurface of the transceiver main body. The latch member 74 is pivoted rotatably on a revolving shaft 76 extending perpendicularly to insertion and extraction directions along the undersurface of the transceiver main body at a position outside an instrument (in other words, the left side) from the vertical plane 75. As a matter of course, the transceiver main body maintains a space, which can contain the latch member 74, inside thereof without extending beyond the undersurface 71 of the transceiver main body in the case when the latch member 74 is rotated.
As shown in FIG. 1B, when the latch member 74 is rotated counterclockwise around the revolving shaft 76 to enter a space inside the transceiver main body, the vertical plane 75 does not abut upon the port 73, whereby a locking state of the latch member is released. Although it is not shown in the drawing, but omitted, a transceiver head which exposes outside the host instrument is integrated with the transceiver main body, and further, another movable member is disposed on the transceiver head for operating rotatably the latch member 74.
In FIGS. 2A and 2B, an essential part of a locking mechanism disclosed in U.S. Pat. No. 5,980,324 is shown.
The locking mechanism shown in FIG. 2A involves a fixed projection 84 which functions to restrict extraction of a transceiver main body (a movement towards the left side in the drawing) as a result of fitting the fixed projection into a hole 83 formed on the undersurface of a cage 82 so as to protrude from the undersurface 81 of the transceiver main body. The fixed projection 84 is in a fixed state with respect to the transceiver main body, and the fixed projection 84 contains a vertical plane 85 which outgoes vertically from the undersurface of the transceiver main body.
As shown in FIG. 2B, an area around the hole 83 in the undersurface of the cage 82 is made of a leaf spring 86 an end of which is a free end on the external side of an instrument for the transceiver main body. When the leaf spring 86 is directed downwards, the vertical plane 85 does not abut upon the hole 83, whereby a locking state of the fixed projection is released. Although it is not shown in the drawing, but omitted, a transceiver head which exposes outside the host instrument is integrated with the transceiver main body, and further, amovable member is disposed on the transceiver head for operating to direct the leaf spring 86 towards the downward direction.
In the locking mechanism shown in FIGS. 1A and 1B, the latch member 74 incorporated in the transceiver main body moves to disengage from the port 73 in the cage 72. On one hand, in the locking mechanism shown in FIGS. 2A and 2B, a part of the cage 82 rises to disengage the fixed projection 84, which is fixed to the transceiver main body, from the hole 83 in the cage 82.
In both the cases in common, however, the vertical planes 75 and 85 abut upon edges of the port 73 or the hole 83 in the cages 72 and 82, so that the vertical planes 75 and 85 go out from the port 73 or the hole 83 while keeping a friction with the edges of the port 73 or the hole 83, respectively. Since the port 73 or the hole 83 is fabricated by punching out the cage 72 or 82 made of a sheet metal, the resulting edge has a sharp surface. Under the circumstances, the vertical plane 75 or 85 scrapes against the edge of the port 73 or the hole 83, so that there is a case where the latch member 74 or the fixed projection 84 is damaged or worn away, resulting in an unreliable latch condition. Besides, when swarf produced by such scraping flies in all directions inside and outside the host instrument, it causes hindrance in optical connection or electrical troubles.